Hi all.. I am researching and considering evacuated tube collectors since we live in Canada. Do we need to dig a loop in the ground for a heat dump in the event that the heat exchanger is supplying too much heat to the storage tank in the summer? We don't have a pool.

The answer to the question lies in the particulars of the design.

If by-design iit's sized such that you need a heat dump, a buried loop can do the trick (if properly designed), but that may not be the cheapest way to go. You can do a lot with fin-tube baseboard in a well-ventilated area (but you have to do the math on that too.) Any system designer worth their salt will find a reasonable solution that fits.

Most domestic hot water (DHW) installations are sized to not need seasonal heat dumping, but most space heating apps will need at least some. With evacuated tubes the energetic can get away with twisting them in place to reduce the solar gain in the summer, but that's only as reliable as the operator. Alternatively , seasonally shading the collectors either partially or fully also works for systems designed without heat dumping capacity. (Something to think about even with DHW systems with evacuated tubes if you're leaving for a week of vacation during the summer.) Flat panels can be their own heat dump if controlled to pump away at night to radiate away the heat, but there can be a fair amount of pumping electricity expended. Fin-tube heat dumps are usually more efficient from a power-use point of view.

You should look at EnerWorks solar system. They have solved the overheating problem with a self-regulating solar collector design. They are also a Canadian company, located near Toronto I think.